WASHINGTON (CNN) -- Many of the nation's leading civil rights groups expressed "serious concern" Monday with President Bush's nomination of White House Counsel Alberto Gonzales to be attorney general, calling for "close scrutiny" by the Senate.

But the coalition of more than two dozen groups -- including the NAACP, ACLU and Amnesty International -- stopped short of opposing the nomination.

Gonzales is expected to face tough questions during his confirmation hearings, particularly about a January 2002 draft memo he wrote.

The memo warned Bush administration officials that they could be held accountable for "war crimes" if they did not agree with the conclusion of Justice Department attorneys that the Geneva Conventions do not apply to al Qaeda and Taliban detainees held at Guantanamo Bay, Cuba.

In a joint letter to Senate Judiciary Committee Chairman Sen. Orrin Hatch, a Utah Republican, and ranking Democratic member Sen. Patrick Leahy of Vermont, the organizations listed concerns about Gonzales' role in the administration's policy on detention, interrogation and torture of captured battlefield prisoners and terrorism suspects.

"Changes made as a result to long-established U.S. policy and practice paved the way for the horrific torture at Abu Ghraib," the letter said, referring to the Iraqi prison where physical and sexual abuse has led to charges and convictions against several U.S. soldiers.

"We strongly urge that you engage in a searching and thorough review of Mr. Gonzales' record, his positions, and his future plans for the Justice Department," the letter said.

It also urged the committee to determine whether Gonzales will continue the "troubling record of outgoing Attorney General John Ashcroft."

Ashcroft has garnered criticism during his nearly four years as attorney general over issues like the Patriot Act, which backers say helps the government in its fight against terrorism and critics say infringes on civil liberties.

A former Texas Supreme Court justice and White House counsel since Bush took office in January 2001, Gonzales was nominated November 10. (Full story)

"His sharp intellect and sound judgment have helped shape our policies in the war on terror," Bush said at the time. "He has an unwavering principle of respect for the law."

Among the organizations signing the letter was Human Rights Watch, which had earlier issued a statement calling the nomination "a poor choice," based on Gonzales' January 2002 memo and his support of military tribunals to try terror war detainees.

Missing from the list of signatories is the Center for Constitutional Rights, which has issued a statement voicing "strong opposition" to the nomination, for reasons similar to those of Human Rights Watch.

"I can assure you our position opposed to the nomination has not changed," said David Lerner, spokesman for the organization.

A senior Justice Department official, noting the letter's lack of outright opposition to Gonzales, said the stance reflected a recognition of political realities.

"They obviously want the confirmation to be a bumpy ride, but these groups are politically savvy enough to know that opposing a highly qualified Latino nominee would not serve their interests," the official said.

Gonzales would be the first Hispanic to serve as attorney general.

'A more uniting figure'

After meeting with Gonzales on Capitol Hill earlier this month, Leahy told reporters that the nominee was "a more uniting figure" than Ashcroft, adding that Gonzales "has a far better chance of confirmation with substantial votes from both sides of the aisle than a divisive candidate."

Leahy said he warned Gonzales the subject of the 2002 memo would be raised extensively in the confirmation hearings and that he must respond to the questions.

"I think it's important for his own credibility" and the credibility of the Department of Justice, Leahy said.